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NAME="VIDIOC-QUERYSTD"
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>ioctl VIDIOC_QUERYSTD</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN13645"
></A
><H2
>Name</H2
>VIDIOC_QUERYSTD&nbsp;--&nbsp;Sense the video standard received by the current
input</DIV
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><H2
>Synopsis</H2
><DIV
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><P
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><A
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></A
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int ioctl</CODE
>(int fd, int request, v4l2_std_id *argp);</CODE
></P
><P
></P
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><A
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></A
><H2
>Arguments</H2
><P
></P
><DIV
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><DL
><DT
><CODE
CLASS="PARAMETER"
>fd</CODE
></DT
><DD
><P
>File descriptor returned by <A
HREF="r14090.htm"
><CODE
CLASS="FUNCTION"
>open()</CODE
></A
>.</P
></DD
><DT
><CODE
CLASS="PARAMETER"
>request</CODE
></DT
><DD
><P
>VIDIOC_QUERYSTD</P
></DD
><DT
><CODE
CLASS="PARAMETER"
>argp</CODE
></DT
><DD
><P
></P
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><A
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><H2
>Description</H2
><P
>The hardware may be able to detect the current video
standard automatically. To do so, applications call <CODE
CLASS="CONSTANT"
>VIDIOC_QUERYSTD</CODE
> with a pointer to a <A
HREF="r9288.htm#V4L2-STD-ID"
>v4l2_std_id</A
> type. The
driver stores here a set of candidates, this can be a single flag or a
set of supported standards if for example the hardware can only
distinguish between 50 and 60 Hz systems. When detection is not
possible or fails, the set must contain all standards supported by the
current video input or output.</P
></DIV
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><H2
>Return Value</H2
><P
>On success <SPAN
CLASS="RETURNVALUE"
>0</SPAN
> is returned, on error <SPAN
CLASS="RETURNVALUE"
>-1</SPAN
> and the <CODE
CLASS="VARNAME"
>errno</CODE
> variable is set appropriately:</P
><P
></P
><DIV
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><DL
><DT
><SPAN
CLASS="ERRORCODE"
>EINVAL</SPAN
></DT
><DD
><P
>This ioctl is not supported.</P
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